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1. \( y(0) = 2 \):
\[ C_1 + C_2 = 2 \]
2. \( y'(t) = \frac{\sqrt{15}}{5} C_1 e^{\frac{\sqrt{15}}{5} t} - \frac{\sqrt{15}}{5} C_2 e^{-\frac{\sqrt{15}}{5} t} \]
Plugging \(t = 0\):
\[ \frac{\sqrt{15}}{5}(C_1 - C_2) = 0 \]
\[ C_1 = C_2 \]
Substituting \(C_1 = C_2\) into the first condition:
\[ 2C_1 = 2 \]
\[ C_1 = 1 \quad \text{and} \quad C_2 = 1 \]
Thus, the solution is:
$$
\[ y(t) = e^{\frac{\sqrt{15}}{5} t} + e^{-\frac{\sqrt{15}}{5} t} \]
$